DOTS T. Reddy
Internet-Draft McAfee
Intended status: Standards Track M. Boucadair
Expires: December 24, 2017 Orange
K. Nishizuka
NTT Communications
L. Xia
Huawei
P. Patil
Cisco
A. Mortensen
Arbor Networks, Inc.
N. Teague
Verisign, Inc.
June 22, 2017
Distributed Denial-of-Service Open Threat Signaling (DOTS) Data Channel
draft-ietf-dots-data-channel-02
Abstract
The document specifies a Distributed Denial-of-Service Open Threat
Signaling (DOTS) data channel used for bulk exchange of data not
easily or appropriately communicated through the DOTS signal channel
under attack conditions. This is a companion document to the DOTS
signal channel specification.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 24, 2017.
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Internet-Draft DOTS Data Channel June 20171. Introduction
A distributed denial-of-service (DDoS) attack is an attempt to make
machines or network resources unavailable to their intended users.
In most cases, sufficient scale can be achieved by compromising
enough end-hosts and using those infected hosts to perpetrate and
amplify the attack. The victim in this attack can be an application
server, a client, a router, a firewall, or an entire network.
DDoS Open Threat Signaling (DOTS) defines two channels: signal and
data channels [I-D.ietf-dots-architecture] (Figure 1). The DOTS
signal channel used to convey that a network is under a DDOS attack
to an upstream DOTS server so that appropriate mitigation actions are
undertaken on the suspect traffic is further elaborated in
[I-D.ietf-dots-signal-channel]. The DOTS data channel is used for
infrequent bulk data exchange between DOTS agents in the aim to
significantly augment attack response coordination.
+---------------+ +---------------+
| | <------- Signal Channel ------> | |
| DOTS Client | | DOTS Server |
| | <======= Data Channel ======> | |
+---------------+ +---------------+
Figure 1: DOTS Channels
Section 2 of [I-D.ietf-dots-architecture] identifies that the DOTS
data channel is used to perform the tasks listed below:
o Filter management, which enables a DOTS client to request the
installation or removal of traffic filters, dropping or rate-
limiting unwanted traffic and permitting white-listed traffic.
Sample use cases for populating black- or white-list filtering
rules are detailed hereafter:
A. If a network resource (DOTS client) detects a potential DDoS
attack from a set of IP addresses, the DOTS client informs its
servicing router (DOTS gateway) of all suspect IP addresses
that need to be blocked or black-listed for further
investigation. The DOTS client could also specify a list of
protocols and ports in the black-list rule. That DOTS gateway
in-turn propagates the black-listed IP addresses to the DOTS
server which will undertake appropriate action so that traffic
from these IP addresses to the target network (specified by
the DOTS client) is blocked.
B. A network has partner sites from which only legitimate traffic
arrives and the network wants to ensure that the traffic from
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these sites is not penalized during DDOS attacks. The DOTS
client uses the DOTS data channel to convey the white-listed
IP addresses or prefixes of the partner sites to its DOTS
server. The DOTS server uses this information to white-list
flows from such IP addresses or prefixes reaching the network.
o Creating identifiers, such as names or aliases, for resources for
which mitigation may be requested:
A. The DOTS client may submit to the DOTS server a collection of
prefixes which it would like to refer to by alias when
requesting mitigation. The server can respond to this request
with either with a success or failure response (see
requirement OP-006 in [I-D.ietf-dots-requirements] and
Section 2 in [I-D.ietf-dots-architecture]).
2. Notational Conventions and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
The reader should be familiar with the terms defined in
[I-D.ietf-dots-architecture].
For simplicity, all of the examples in this document use "/restconf"
as the discovered RESTCONF API root path. Many protocol header lines
and message-body text within examples throughout the document are
split into multiple lines for display purposes only. When a line
ends with backslash ('\') as the last character, the line is wrapped
for display purposes. It is to be considered to be joined to the
next line by deleting the backslash, the following line break, and
the leading whitespace of the next line.
3. DOTS Data Channel
The DOTS data channel is intended to be used for bulk data exchanges
between DOTS agents. Unlike the signal channel, which must operate
nominally even when confronted with signal degradation due to packet
loss, the data channel is not expected to be constructed to deal with
DDoS attack conditions.
As the primary function of the data channel is data exchange, a
reliable transport is required in order for DOTS agents to detect
data delivery success or failure. RESTCONF [RFC8040] over TLS
[RFC5246] over TCP is used for DOTS data channel (Figure 2).
RESTCONF uses HTTP methods to provide CRUD operations on a conceptual
datastore containing YANG-defined data, which is compatible with a
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server which implements NETCONF datastores. The HTTP POST, PUT,
PATCH, and DELETE methods are used to edit data resources represented
by DOTS data channel YANG data models. These basic edit operations
allow the DOTS data channel running configuration to be altered by a
DOTS client. DOTS data channel configuration data and state data can
be retrieved with the GET method. HTTP status codes are used to
report success or failure for RESTCONF operations. The DOTS client
will perform the root resource discovery procedure discussed in
Section 3.1 of [RFC8040] to determine the root of the RESTCONF API.
After discovering the RESTCONF API root, the DOTS client MUST use
this value as the initial part of the path in the request URI, in any
subsequent request to the DOTS server. The DOTS server can
optionally support retrieval of the YANG modules it supports
(Section 3.7 in [RFC8040]), for example, DOTS client can use RESTCONF
to retrieve the company proprietary YANG model supported by the DOTS
server.
Note: This document uses RESTCONF, a protocol based on HTTP
[RFC7230], for configuring data defined in YANG version 1 [RFC6020]
or YANG version 1.1 [RFC7950], using the datastore concepts defined
in the Network Configuration Protocol (NETCONF) [RFC6241]. RESTCONF
combines the simplicity of the HTTP protocol with the predictability
and automation potential of a schema-driven API. RESTCONF offers a
simple subset of NETCONF functionality and provides a simplified
interface using REST-like API which addresses the needs of the DOTS
data channel and hence an optimal choice.
+--------------+
| DOTS |
+--------------+
| RESTCONF |
+--------------+
| TLS |
+--------------+
| TCP |
+--------------+
| IP |
+--------------+
Figure 2: Abstract Layering of DOTS data channel over RESTCONF over
TLS
JavaScript Object Notation (JSON) [RFC7159] payload is used to
propagate data channel specific payload messages that convey request
parameters and response information such as errors. This
specification uses the encoding rules defined in [RFC7951] for
representing DOTS data channel configuration data defined using YANG
(Section 3.1) as JSON text.
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A DOTS client registers itself to its DOTS server(s) in order to set
up DOTS data channel related configuration data on the DOTS server
and receive state data (i.e., non-configuration data) from the DOTS
server. A single DOTS data channel between DOTS agents can be used
to exchange multiple requests and multiple responses. To reduce DOTS
client and DOTS server workload, DOTS client SHOULD re-use the TLS
session. While the communication to the DOTS server is quiescent,
the DOTS client MAY probe the server to ensure it has maintained
cryptographic state. Such probes can also keep alive firewall or NAT
bindings. A TLS heartbeat [RFC6520] verifies the DOTS server still
has TLS state by returning a TLS message.
3.1. DOTS Data Channel YANG Model3.1.1. Identifier Model structure
This document defines a YANG [RFC6020] data model for creating
identifiers, such as names or aliases, for resources for which
mitigation may be requested. Such identifiers may then be used in
subsequent DOTS signal channel exchanges to refer more efficiently to
the resources under attack.
This document defines the YANG module "ietf-dots-data-channel-
identifier", which has the following structure:
module: ietf-dots-data-channel-identifier
+--rw identifier
+--rw alias* [alias-name]
+--rw alias-name string
+--rw ip* inet:ip-address
+--rw prefix* inet:ip-prefix
+--rw port-range* [lower-port upper-port]
| +--rw lower-port inet:port-number
| +--rw upper-port inet:port-number
+--rw traffic-protocol* uint8
+--rw fqdn* inet:domain-name
+--rw uri* inet:uri
3.1.2. Identifier Model
<CODE BEGINS> file "ietf-dots-data-channel-identifier@2016-11-28.yang"
module ietf-dots-data-channel-identifier {
namespace "urn:ietf:params:xml:ns:yang:ietf-dots-data-channel-identifier";
prefix "alias";
import ietf-inet-types {
prefix "inet";
}
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}
leaf-list traffic-protocol {
type uint8;
description "Internet Protocol number";
}
leaf-list fqdn {
type inet:domain-name;
description "FQDN";
}
leaf-list uri {
type inet:uri;
description "URI";
}
}
}
}
<CODE ENDS>
3.1.3. Filter Model structure
This document extends the "ietf-access-control-list" Access Control
List (ACL) YANG data model [I-D.ietf-netmod-acl-model] for the
configuration of filtering rules. ACL is explained in Section 1 of
[I-D.ietf-netmod-acl-model].
Examples of such configuration include:
o Black-list management, which enables a DOTS client to inform the
DOTS server about sources from which traffic should be suppressed.
o White-list management, which enables a DOTS client to inform the
DOTS server about sources from which traffic should always be
accepted.
o Filter management, which enables a DOTS client to request the
installation or removal of traffic filters, dropping or rate-
limiting unwanted traffic and permitting white-listed traffic.
This document defines the YANG module "ietf-dots-access-control-list"
to extend the "ietf-access-control-list" module to handle fragmented
packets and to support rate-limit action. Filtering fragments adds
an additional layer of protection against a denial-of-service (DoS)
attack that uses only noninitial fragments. When there is only Layer
3 information in the ACL entry and the fragments keyword is present,
for noninitial fragments matching the ACL entry, the deny or permit
action associated with the ACL entry will be enforced and for initial
or non-fragment matching the ACL entry, the the next ACL entry will
be processed. When there is both Layer 3 and Layer 4 information in
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the ACL entry and the fragments keyword is present, the ACL action is
conservative for both permit and deny actions. The actions are
conservative to not accidentally deny a fragmented portion of a flow
because the fragments do not contain sufficient information to match
all of the filter attributes. In the deny action case, instead of
denying a non-initial fragment, the next ACL entry is processed. In
the permit case, it is assumed that the Layer 4 information in the
packet, if available, matches the Layer 4 information in the ACL
entry.
The "ietf-dots-access-control-list" module has the following
structure:
module: ietf-dots-access-control-list
augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:access-list-entries/ietf-acl:ace/ietf-acl:actions/ietf-acl:packet-handling:
+--:(rate-limit)
+--rw rate-limit? decimal64
augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:access-list-entries/ietf-acl:ace:
+--rw fragments? empty
3.1.4. Filter Model
This YANG module augments the "ietf-access-control-list" YANG data
model defined in [I-D.ietf-netmod-acl-model].
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alias-name: Name of the alias. This is a mandatory attribute.
traffic-protocol: Internet Protocol numbers. This is an optional
attribute.
port-range: The port range, lower-port for lower port number and
upper-port for upper port number. For TCP, UDP, SCTP, or DCCP:
the range of ports (e.g., 80 to 8080). This is an optional
attribute.
ip: IP addresses are separated by commas. This is an optional
attribute.
prefix: Prefixes are separated by commas. This is an optional
attribute.
fqdn: Fully Qualified Domain Name, is the full name of a system,
rather than just its hostname. For example, "venera" is a
hostname, and "venera.isi.edu" is an FQDN. This is an optional
attribute.
uri: Uniform Resource Identifier (URI). This is an optional
attribute.
In the POST request at least one of the attributes ip or prefix or
fqdn or uri MUST be present. DOTS agents can safely ignore Vendor-
Specific parameters they don't understand.
Figure 4 shows a POST request to create alias called "https1" for
HTTP(S) servers with IP addresses 2001:db8:6401::1 and
2001:db8:6401::2 listening on port 443.
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POST /restconf/data/ietf-dots-data-channel-identifier HTTP/1.1
Host: www.example.com
Content-Format: "application/yang.api+json"
{
"ietf-dots-data-channel-identifier:identifier": {
"alias": [
{
"alias-name": "Server1",
"traffic-protocol": [
6
],
"ip": [
"2001:db8:6401::1",
"2001:db8:6401::2"
],
"port-range": [
{
"lower-port": 443
}
]
}
]
}
}
Figure 4: POST to create identifiers
The DOTS server indicates the result of processing the POST request
using HTTP response codes. HTTP 2xx codes are success, HTTP 4xx
codes are some sort of invalid requests and 5xx codes are returned if
the DOTS server has erred or it is incapable of accepting the alias.
Response code 201 (Created) will be returned in the response if the
DOTS server has accepted the alias. If the request is missing one or
more mandatory attributes then 400 (Bad Request) will be returned in
the response or if the request contains invalid or unknown parameters
then 400 (Invalid query) will be returned in the response. The HTTP
response will include the JSON body received in the request.
The DOTS client can use the PUT request (Section 4.5 in [RFC8040]) to
create or modify the aliases in the DOTS server.
3.2.2. Delete Identifiers
A DELETE request is used to delete identifiers maintained by a DOTS
server (Figure 5).
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DELETE /restconf/data/ietf-dots-data-channel-identifier:identifier\
/alias=Server1 HTTP/1.1
Host: {host}:{port}
Figure 5: DELETE identifier
In RESTCONF, URI-encoded path expressions are used. A RESTCONF data
resource identifier is encoded from left to right, starting with the
top-level data node, according to the "api-path" rule defined in
Section 3.5.3.1 of [RFC8040]. The data node in the above path
expression is a YANG list node and MUST be encoded according to the
rules defined in Section 3.5.1 of [RFC8040].
If the DOTS server does not find the alias name conveyed in the
DELETE request in its configuration data, then it responds with a 404
(Not Found) error response code. The DOTS server successfully
acknowledges a DOTS client's request to remove the identifier using
204 (No Content) in the response.
3.2.3. Retrieving Installed Identifiers
A GET request is used to retrieve the set of installed identifiers
from a DOTS server (Section 3.3.1 in [RFC8040]). Figure 6 shows how
to retrieve all the identifiers that were instantiated by the DOTS
client. The content parameter and its permitted values are defined
in Section 4.8.1 of [RFC8040].
GET /restconf/data/ietf-dots-data-channel-identifier:identifier?\
content=config HTTP/1.1
Host: {host}:{port}
Accept: application/yang-data+json
Figure 6: GET to retrieve all the installed identifiers
Figure 7 shows response for all identifiers on the DOTS server.
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Internet-Draft DOTS Data Channel June 20173.3. Filtering Rules
The DOTS server either receives the filtering rules directly from the
DOTS client or via the DOTS gateway. If the DOTS client signals the
filtering rules via the DOTS gateway then the DOTS gateway validates
if the DOTS client is authorized to signal the filtering rules and if
the client is authorized propagates the rules to the DOTS server.
Likewise, the DOTS server validates if the DOTS gateway is authorized
to signal the filtering rules. To create or purge filters, the DOTS
client sends HTTP requests to the DOTS gateway. The DOTS gateway
validates the rules in the requests and proxies the requests
containing the filtering rules to a DOTS server. When the DOTS
gateway receives the associated HTTP response from the DOTS server,
it propagates the response back to the DOTS client.
The following APIs define means for a DOTS client to configure
filtering rules on a DOTS server.
3.3.1. Install Filtering Rules
A POST request is used to push filtering rules to a DOTS server.
Figure 8 shows a POST request example to block traffic from
192.0.2.0/24, destined to 198.51.100.0/24. The ACL JSON
configuration for the filtering rule is generated using the ACL YANG
data model defined in [I-D.ietf-netmod-acl-model] and the ACL
configuration XML for the filtering rule is specified in Section 4.3
of [I-D.ietf-netmod-acl-model].
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actions: "deny" or "permit" or "rate-limit". "permit" action is
used to white-list traffic. "deny" action is used to black-list
traffic. "rate-limit" action is used to rate-limit traffic, the
allowed traffic rate is represented in bytes per second indicated
in IEEE floating point format [IEEE.754.1985]. If actions
attribute is not specified in the request then the default action
is "deny". This is an optional attribute.
The DOTS server indicates the result of processing the POST request
using HTTP response codes. HTTP 2xx codes are success, HTTP 4xx
codes are some sort of invalid requests and 5xx codes are returned if
the DOTS server has erred or it is incapable of configuring the
filtering rules. Response code 201 (Created) will be returned in the
response if the DOTS server has accepted the filtering rules. If the
request is missing one or more mandatory attributes then 400 (Bad
Request) will be returned in the response or if the request contains
invalid or unknown parameters then 400 (Invalid query) will be
returned in the response.
The DOTS client can use the PUT request to create or modify the
filtering rules in the DOTS server.
3.3.2. Remove Filtering Rules
A DELETE request is used to delete filtering rules from a DOTS server
(Figure 9).
DELETE /restconf/data/ietf-access-control-list:access-lists/acl-name\
=sample-ipv4-acl&acl-type=ipv4 HTTP/1.1
Host: {host}:{port}
Figure 9: DELETE to remove the filtering rules
If the DOTS server does not find the access list name and access list
type conveyed in the DELETE request in its configuration data, then
it responds with a 404 (Not Found) error response code. The DOTS
server successfully acknowledges a DOTS client's request to withdraw
the filtering rules using 204 (No Content) response code, and removes
the filtering rules as soon as possible.
3.3.3. Retrieving Installed Filtering Rules
The DOTS client periodically queries the DOTS server to check the
counters for installed filtering rules. A GET request is used to
retrieve filtering rules from a DOTS server. Figure 10 shows how to
retrieve all the filtering rules programmed by the DOTS client and
the number of matches for the installed filtering rules.
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GET /restconf/data/ietf-access-control-list:access-lists?content=all HTTP/1.1
Host: {host}:{port}
Accept: application/yang-data+json
Figure 10: GET to retrieve the configuration data and state data for
the filtering rules
If the DOTS server does not find the access list name and access list
type conveyed in the GET request in its configuration data, then it
responds with a 404 (Not Found) error response code.
4. IANA Considerations
This specification registers new parameters for the DOTS data channel
and establishes registries for mappings to JSON attributes.
4.1. DOTS Data Channel JSON Attribute Mappings Registry
A new registry will be requested from IANA, entitled "DOTS data
channel JSON attribute Mappings Registry". The registry is to be
created as Expert Review Required.
4.2. Registration Template
JSON Attribute:
JSON attribute name.
Description:
Brief description of the attribute.
Change Controller:
For Standards Track RFCs, list the "IESG". For others, give the
name of the responsible party. Other details (e.g., postal
address, email address, home page URI) may also be included.
Specification Document(s):
Reference to the document or documents that specify the parameter,
preferably including URIs that can be used to retrieve copies of
the documents. An indication of the relevant sections may also be
included but is not required.
4.3. Initial Registry Contents
o JSON Attribute: "alias-name"
o Description: Name of alias.
o Change Controller: IESG
o Specification Document(s): this document
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Internet-Draft DOTS Data Channel June 20175. Contributors
The following individuals have contributed to this document:
Dan Wing
Email: dwing-ietf@fuggles.com
6. Security Considerations
Authenticated encryption MUST be used for data confidentiality and
message integrity. TLS based on client certificate MUST be used for
mutual authentication. The interaction between the DOTS agents
requires Transport Layer Security (TLS) with a cipher suite offering
confidentiality protection and the guidance given in [RFC7525] MUST
be followed to avoid attacks on TLS.
An attacker may be able to inject RST packets, bogus application
segments, etc., regardless of whether TLS authentication is used.
Because the application data is TLS protected, this will not result
in the application receiving bogus data, but it will constitute a DoS
on the connection. This attack can be countered by using TCP-AO
[RFC5925]. If TCP-AO is used, then any bogus packets injected by an
attacker will be rejected by the TCP-AO integrity check and therefore
will never reach the TLS layer.
Special care should be taken in order to ensure that the activation
of the proposed mechanism won't have an impact on the stability of
the network (including connectivity and services delivered over that
network).
Involved functional elements in the cooperation system must establish
exchange instructions and notification over a secure and
authenticated channel. Adequate filters can be enforced to avoid
that nodes outside a trusted domain can inject request such as
deleting filtering rules. Nevertheless, attacks can be initiated
from within the trusted domain if an entity has been corrupted.
Adequate means to monitor trusted nodes should also be enabled.
7. Acknowledgements
Thanks to Christian Jacquenet, Roland Dobbins, Andrew Mortensen,
Roman Danyliw, Ehud Doron, Russ White and Gilbert Clark for the
discussion and comments.
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